This application is related to Japanese Patent Applications No. 2000-164884 filed on Jun. 1, 2000, No. 2001-38998 filed on Feb. 15, 2001, No. 2001-113076 filed on Apr. 11, 2001, No. 2001-128034 filed on Apr. 25, 2001, and No. 2001-128035 filed on Apr. 25, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an ejector cycle system having an ejector. In the ejector, high-pressure side refrigerant is decompressed and expanded so that gas refrigerant evaporated in an evaporator is sucked therein, and a refrigerant pressure to be sucked into a compressor is increased by converting an expansion energy to a pressure energy.
2. Description of Related Art
In an ejector cycle system, when an ejector efficiency xcex7e is low, a refrigerant cycle efficiency is decreased. For example, JP-A-57-129360 discloses an ejector, where a diameter of a mixing portion is 3-7 mm, a length of the mixing portion is 8-12 times of the diameter of the mixing portion, an extension angle of a diffuser is 4-6 degrees, and a length of the diffuser is 10-14 times of the length of the mixing portion. This ejector is tested and studied by the present inventors, but sufficient ejector efficiency xcex7e cannot be obtained.
In view of the foregoing problems, it is an object of the present invention to provide an ejector cycle system which improves an ejector efficiency.
It is an another object of the present invention to provide an ejector cycle system which improves a refrigerating capacity (heat-absorbing capacity) in an evaporator.
According to the present invention, in an ejector cycle system, an ejector includes a nozzle in which a pressure energy of high-pressure side refrigerant flowing from a radiator is converted to a speed energy so that refrigerant is decompressed and expanded, and a pressure-increasing portion in which the speed energy is converted to a pressure energy so that the pressure of refrigerant is increased while refrigerant discharged from the nozzle and refrigerant sucked from an evaporator are mixed. The nozzle is a divergent nozzle having therein a throat portion at which a passage sectional area becomes smallest in a refrigerant passage of the divergent nozzle. Further, the divergent nozzle has a first dimension between the throat portion and an outlet of the nozzle and a second dimension between the throat portion and an upstream portion upstream from the throat portion, from which the passage sectional area becomes smaller in the refrigerant passage of the divergent nozzle, and the first dimension is larger than the second dimension. The pressure-increasing portion has a length in a refrigerant flow direction and a smallest equivalent diameter, a ratio of the length to the smallest equivalent diameter is equal to or smaller than 120, and a ratio of the smallest equivalent diameter of the pressure-increasing portion to an equivalent diameter at the outlet of the nozzle is in a range of 1.05-10. In this case, the ejector cycle system operates while a high ejector efficiency can be maintained.
Preferably, the pressure-increasing portion has a shape so that refrigerant changes substantially along an isentropic curve from a refrigerant inlet to a refrigerant outlet of the pressure-increasing portion. Accordingly, the ejector efficiency can be further improved.
Further, the pressure-increasing portion has a refrigerant passage with a passage section area, and the passage sectional area is approximately constant from an upstream side to a downstream side in the refrigerant passage of the pressure-increasing portion. Alternatively, the passage sectional area is gradually increased from an upstream side to a downstream side in the refrigerant passage of the pressure-increasing portion. Accordingly, the structure of the pressure-increasing portion can be made simple, and the ejector is readily manufactured in low cost.
According to the present invention, in an ejector cycle system, an ejector includes a nozzle in which a pressure energy of high-pressure side refrigerant flowing from a radiator is converted to a speed energy so that refrigerant is decompressed and expanded, a mixing portion in which gas refrigerant evaporated in an evaporator is sucked by a high-speed refrigerant flow ejected from the nozzle to be mixed with refrigerant ejected from the nozzle, and a diffuser in which the speed energy is converted to the pressure energy so that the pressure of refrigerant is increased. The mixing portion has a length in a refrigerant flow direction and an equivalent diameter, and a ratio of the length to the equivalent diameter is equal to or smaller than 120. Further, a ratio of the equivalent diameter of the mixing portion to an equivalent diameter at the outlet of the nozzle is in a range of 1.05-10. In this case, the ejector efficiency more than 20% can be maintained.
Preferably, the refrigerant is carbon dioxide, the ratio of the equivalent diameter of the mixing portion to the equivalent diameter at the outlet of the nozzle is in a range of 1.3-5.3. In this case, the ejector cycle system can operate while the ejector efficiency more than 40% is maintained.
Preferably, the refrigerant is freon, and the ratio of the equivalent diameter of the mixing portion to the equivalent diameter at the outlet of the nozzle is in a range of 1.05-4.5. In this case, the ejector cycle system can operate while the ejector efficiency more than 20% is maintained.
The diffuser has a refrigerant passage with a passage section area, the passage sectional area is gradually increased from an upstream side to a downstream side in the refrigerant passage of the diffuser, the diffuser has an extension angle xcex8d which is defined by an inside wall surface of the diffuser and a reference line parallel to a center axial line of the diffuser, and the extension angle ed of the diffuser is in a range of 0.2-34 degrees. More preferably, the extension angle ed of the diffuser is in a range of 0.2-7 degrees. Accordingly, the ejector efficiency can be further improved.
Preferably, the nozzle has a shape so that refrigerant changes substantially along an isentropic curve from a refrigerant inlet to a refrigerant outlet of the nozzle. Accordingly, even when the refrigerant is a mixing refrigerant such as HFC-404A, HFC-407, HFC-410, because refrigerant changes in the ejector substantially along the isentropic curve, the dryness of refrigerant flowing from the ejector into a gas-liquid separator becomes smaller. Accordingly, even when the mixing refrigerant is used as the refrigerant in the ejector cycle system, a ratio of gas refrigerant contained in refrigerant supplied into the evaporator from the gas-liquid separator becomes smaller, a pressure loss generated while refrigerant is supplied from the gas-liquid separator to the evaporator can be made smaller, and refrigerating capacity (heat-absorbing capacity) of the evaporator can be improved.
According to the present invention, in an ejector cycle system, a nozzle of an ejector has a refrigerant ejecting port from which refrigerant is ejected, the nozzle is connected to a gas-liquid separator in such a manner that, within the gas-liquid separator, gas refrigerant in the evaporator is sucked by a high-speed refrigerant flow ejected from the nozzle, and the speed energy of refrigerant is converted to the pressure energy while refrigerant discharged from the nozzle and refrigerant sucked from the evaporator are mixed. Alternatively, a refrigerant outlet side of a mixing portion of an ejector is connected to the gas-liquid separator in such a manner that, within the gas-liquid separator, the speed energy of refrigerant flowing from the mixing portion is converted to the pressure energy to increase refrigerant pressure. Because the nozzle or the mixing portion of an ejector is integrally connected with the gas-liquid separator, the size of the ejector cycle system can be made smaller, and the elector can be manufactured in low cost.
According to the present invention, in an ejector cycle system, an ejector includes a first nozzle in which a pressure energy of high-pressure side refrigerant flowing from the radiator is converted to a speed energy so that refrigerant is decompressed and expanded, a second nozzle disposed around the first nozzle in such a manner that refrigerant from the evaporator is sucked and is ejected by a refrigerant flow ejected from the first nozzle, and a pressure-increasing portion in which the speed energy is converted to the pressure energy so that the pressure of refrigerant is increased while refrigerant ejected from the first nozzle and refrigerant ejected from the second nozzle are mixed. The first nozzle has a first injecting port from which refrigerant from a radiator is injected, the second nozzle has a second injecting port from which refrigerant from the evaporator is injected, and the first injecting port and the second injecting port are provided at an approximately equal position in a refrigerant passage of the ejector in a refrigerant flow direction. Accordingly, the ejector cycle performance can be improved.
According to the present invention, in an ejector cycle system, an ejector includes a nozzle in which a pressure energy of high-pressure side refrigerant flowing from a radiator is converted to a speed energy so that refrigerant is decompressed and expanded, a mixing portion in which gas refrigerant evaporated in an evaporator is sucked by a high-speed refrigerant flow ejected from the nozzle to be mixed with refrigerant ejected from the nozzle, and a diffuser in which the speed energy is converted to the pressure energy so that the pressure of refrigerant is increased. The ejector is constructed in such a manner that refrigerant from the mixing portion flows into the diffuser after a flow rate of refrigerant sucked from the evaporator and a flow rate of refrigerant ejected from the nozzle becomes approximately equal in the mixing portion. Accordingly, in the ejector, refrigerant pressure can be sufficiently increased in the mixing portion and the diffuser, and the ejector efficiency can be improved.
According to the present invention, in an ejector cycle system, an ejector is constructed so that a pressure-increasing ratio of a pressure-increasing amount in a mixing portion to an entire pressure-increasing amount in the ejector is set to be equal to or larger than 50% when carbon dioxide is used as refrigerant. Preferably, the pressure-increasing ratio of the pressure-increasing amount in the mixing portion to the entire pressure-increasing amount in the ejector is set in a range of 55-80% when carbon dioxide is used as refrigerant. In this case, the ejector efficiency can be improved.
Alternatively, an ejector is constructed so that a pressure-increasing ratio of a pressure-increasing amount in a mixing portion to an entire pressure-increasing amount in the ejector is set to be equal to or larger than 30% when freon is used as refrigerant. Preferably, the pressure-increasing ratio of the pressure-increasing amount in the mixing portion to the entire pressure-increasing amount in the ejector is set in a range of 35-80% when freon is used as refrigerant. In this case, the ejector efficiency can be also improved.